CYTB (Mitochondrial Cytochrome b) Gene
Essential Component of Mitochondrial Complex III: Genetics, Function, and Clinical Significance
Gene Information Card
| Symbol | CYTB |
|---|---|
| Full Name | Cytochrome b (mitochondrial) |
| Gene Type | Protein coding (mitochondrial) |
| Chromosomal Location | Mitochondrial DNA (MT) position 14,747–15,887 (NC_012920.1) |
| NCBI Gene ID | 4519 ncbi.nlm.nih.gov/gene/4519 |
| Ensembl ID | ENSG00000270008 |
| UniProt ID | P00156 |
| OMIM ID | 516020 |
| HGNC ID | 7427 |
| Aliases | MT-CYB, MTCYB, cytochrome b of complex III |
Description
The CYTB gene encodes cytochrome b, a key subunit of mitochondrial Complex III (ubiquinol-cytochrome c reductase) in the electron transport chain. It is located on mitochondrial DNA (mtDNA) and is essential for oxidative phosphorylation, contributing to ATP production. CYTB mutations are associated with various mitochondrial disorders, including exercise intolerance, Leber hereditary optic neuropathy (LHON), and multisystem diseases.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Leber hereditary optic neuropathy (LHON) | Mitochondrial dysfunction leading to impaired ATP production and increased reactive oxygen species in retinal ganglion cells | ClinVar, OMIM |
| Exercise intolerance | Reduced Complex III activity impairing skeletal muscle energy metabolism | ClinVar, OMIM |
| Mitochondrial encephalomyopathy | Disruption of oxidative phosphorylation causing neurological and muscular symptoms | ClinVar, OMIM |
| Cardiomyopathy | Complex III deficiency affecting cardiac muscle energy supply | ClinVar, OMIM |
| Multisystem mitochondrial disorder | Heteroplasmic mutations causing variable tissue-specific defects | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | High | High |
| Skeletal Muscle | High | High |
| Liver | Moderate | Moderate |
| Brain | Moderate | Moderate |
| Kidney | Moderate | Moderate |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | High | Mitochondrial-rich cell line |
| HepG2 | High | Hepatocellular carcinoma cell line |
| SH-SY5Y | Moderate | Neuroblastoma cell line |
| A549 | Moderate | Lung carcinoma cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| m.14846G>A (p.Gly251Ser) | Missense | Rare | Reduced Complex III activity, associated with exercise intolerance |
| m.15257G>A (p.Asp171Asn) | Missense | Low | Associated with LHON, alters electron transfer |
| m.15059G>A (p.Gly78Ser) | Missense | Rare | Impaired Complex III assembly, myopathy |
| m.14798T>C (p.Phe18Leu) | Missense | Low | Possible modifier in LHON |
| m.14849T>C (p.Ser35Pro) | Missense | Rare | Severe Complex III deficiency, multisystem disorder |
Mutation functional classification
Loss of Function (LOF)
Most CYTB missense mutations cause partial or complete loss of Complex III activity, leading to impaired oxidative phosphorylation and energy deficiency.
Gain of Function (GOF)
No known gain-of-function mutations; CYTB mutations typically result in loss of function.
Dominant Negative (DN)
Not applicable; CYTB is mitochondrial and inherited maternally, with heteroplasmy influencing phenotype.
View complete mutation data：
Gene Ontology (GO)
| • electron transfer activity | • ubiquinol-cytochrome-c reductase activity |
| • mitochondrial electron transport | • ubiquinol to cytochrome c |
| • integral component of mitochondrial inner membrane | • respiratory chain complex III |
Pathways
• Oxidative phosphorylation (OXPHOS)
• Electron transport chain (Complex III)
• ATP synthesis
Protein Summary
Cytochrome b is a 380-amino acid protein (UniProt P00156) that forms the catalytic core of Complex III. It contains two ubiquinone/ubiquinol binding sites (Qo and Qi) and two b-type heme groups (bL and bH), facilitating electron transfer from ubiquinol to cytochrome c. The protein is highly conserved and critical for proton translocation across the inner mitochondrial membrane, contributing to the proton gradient used for ATP synthesis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CYTB Knockout HEK293 Cell Line | EDJ-KQ5252 | Human | 4519 | Details Get a Quote |
| CYTB Knockout HCT 116 Cell Line | EDJ-KQ27052 | Human | 4519 | Details Get a Quote |
| CYTB Knockout A-549 Cell Line | EDJ-KQ28287 | Human | 4519 | Details Get a Quote |
| CYTB Knockout HeLa Cell Line | EDJ-KQ28288 | Human | 4519 | Details Get a Quote |
